Device for measuring the amount of free fluid in a colloid in a horizontal position

A device for testing the amount of free fluid in a colloid comprises: a first container, wherein the first container has a central axis that spans the length of the first container, wherein the length of the first container is greater than the width and height of the first container, and wherein the central axis of the first container is oriented in a substantially horizontal position during the testing. Methods of using the device include: optically determining the height of free fluid in the container after the period of time has elapsed and using a formula to determine the volume of the free fluid; or removing a plug from a plug tube that is operationally connected to the container; and draining the free fluid from the container into a measurement device.